System and method for tissue specific MR imaging of metabolites using spectral-spatially formed stimulated echo

Abstract

A system for magnetic resonance (MR) spectroscopy includes a plurality of gradient coils positioned about a bore of a magnet and an RF coil assembly coupled to a pulse generator to emit RF pulse sequences and arranged to receive resulting MR signals from a subject of interest. A system control is also included in the MR spectroscopy system and is coupled to the plurality of gradient coils and the RF coil assembly. The system control is programmed to cause the RF coil assembly to emit a first RF pulse and a second RF pulse, wherein at least one of the first and second RF pulses is spectrally selective and at least one of the first and second RF pulses is spatially selective. The system control is also programmed to cause the RF coil assembly to emit a third RF pulse after a pre-defined time delay to generate a stimulated echo and detect MR signals resulting from the stimulated echo.

Description

BACKGROUND OF THE INVENTION[0001]Embodiments of the invention relate generally to magnetic resonance (MR) imaging, and more particularly, to tissue-specific MR imaging of metabolites using spectral-spatially formed stimulated echoes.[0002]When a substance such as human tissue is subjected to a uniform magnetic field (polarizing field B0), the individual magnetic moments of the spins in the tissue attempt to align with this polarizing field, but precess about it in random order at their characteristic Larmor frequency. If the substance, or tissue, is subjected to a magnetic field (excitation field B1) which is in the x-y plane and which has a frequency near the Larmor frequency, the net aligned moment, or “longitudinal magnetization”, Mz, may be rotated, or “tipped”, into the x-y plane to produce a net transverse magnetic moment Mt. A signal is emitted by the excited spins after the excitation signal B1 is terminated and this signal may be received and processed to form an image.[000...

AI Technical Summary

Benefits of technology

[0009]In accordance with yet another aspect of the invention, a computer readable storage medium includes a computer program stored thereon that represents a sequence of instructions that, when executed by a computer, causes the computer to request transmission of a spectral-spatial pulse at a first frequency and request transmission of a follow-up RF pulse, with the spectral-spatial pulse and the follow-up RF pulse generating a spin echo. The sequence of instructions also causes the computer to request transmission of at least one read RF pulse encompassing one or more frequencies, with the spectral-spatial pulse, the follow-up RF pulse, and the at least one read RF pulse generating a stimulated echo. The sequence of instructions further causes the computer to acquire magnetic resonance (MR) signals from the spin echo and the stimulated echo to generate a spectroscopic image and store the MR signals in computer memory.

Problems solved by technology

While CSI, as a sequence for imaging hyperpolarized substances, provides valuable information on tissue type and health of that tissue, prior art CSI does not distinguish where or when metabolic products are formed in a 13C-hyperpolarized metabolic imaging acquisition.

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